1. Field of the Invention
This invention relates to generally to the formation of silicon films. More specifically, the invention relates to silicon precursors for low temperature deposition of silicon films.
2. Background of the Invention
Silicon-containing dielectric deposition is commonly used in the fabrication of integrated circuits. For example, silicon nitride can be used in semiconductor devices as diffusion barriers, gate insulators, in trench isolation and capacitor dielectrics. Low temperature chemical vapor deposition (CVD) is one of the widely used methods in the semiconductor industry for silicon-containing film fabrication.
In the fabrication of devices, a thin passive layer of a chemically inert dielectric material such as, silicon nitride is required. This layer functions as diffusion masks, oxidation barriers, intermetallic dielectric material with high dielectric breakdown voltages and passivation layers. Typically, the nitride films are used as side wall spacers in the memory devices and, with oxides, oxynitrides, as well as gate dielectrics for the transistors.
The most commonly used precursor in semiconductor manufacture for silicon nitride growth is bis(tertiary-butylamino silane) (BTBAS), which requires high temperature (>600° C.) in the chemical vapor deposition processes in order for forming high quality silicon nitride films. This high temperature process temperature requirement is incompatible with the next generation integrated circuit (IC) device manufacturing, where deposition temperature of below 500° C. is desired. Other popular precursors used for silicon film application include dichlorosilane, hexachlorodisilane and ammonia. But these precursors still are problematic. For example, silane and dichlorosilane are pyrophoric, meaning these compounds may spontaneously ignite at high temperatures and form toxic gases. In addition, films manufactured from dichlorosilane may contain contaminants, such as chlorine and ammonium chloride.
Consequently, there is a need for silicon precursor compounds having a low vaporization temperature and an acceptable film deposition rate that do not have the associated problems with present precursor compounds.